Air cargo containers have been used for the transportation of cargo by aircraft for many years. Cargo such as cartons, smaller shipping containers, etc. is first loaded into containers. The containers are then loaded into an aircraft. Use of air cargo containers is much faster than loading cargo directly into the cargo space of the aircraft, since the individual cartons need not be separately placed and secured within the aircraft. The air cargo containers can also be loaded at locations remote from the airport. Furthermore, because the cargo containers are typically designed and constructed to correspond to the interior dimensions of the aircraft cargo space, the containers fit more securely in the cargo space and do not shift during flight. These and other advantages of air cargo containers have made air cargo containers widely used in the air freight and airline industry.
As with most equipment used on aircraft, two primary design goals for air cargo containers are that they be both strong and lightweight. A typical air cargo container includes a base which is typically a flat rectangular aluminum pallet. Two side walls, a rear wall, a front wall, and a roof or lid are attached to the base. The front or outside wall is typically curved to match the curvature of the fuselage of a cargo plane. For the purposes of explanation only, the curved side of the container is referred to here as the front side or wall, and the opposite and flat side is referred here as the back side.
A door is typically included in the flat vertical rear wall of the container so that cargo may be loaded into, and unloaded out of, the container. As illustrated in the prior art container 10 of FIG. 1, a roll-up door 16 is used to close off the flat rear side of the cargo container 10. The roll-up door moves straight up and down. When cargo 12 is loaded from the rear toward the front curved wall 14 of the container 10, the cargo 12 can generally be loaded flat against the front wall only up to the height where the curvature begins, designated by dimension A in FIG. 1, typically about 36–60, 40–56, 44–52 inches. Since the cargo 12 generally consists primarily of square or rectangular boxes, much of the useable space under the curved section of the wall 14 of the air cargo container 10 is not usable.
In response to this problem, air cargo containers have been developed that include a flexible door in the curved front wall of the container. These flexible doors typically include netting that is buckled together, using several straps and buckles, both horizontally and vertically along the flexible door opening. The bottom ends of the horizontal straps are secured to the pallet with standard aircraft pallet fittings. A weather cover is incorporated into the netting. The weather cover is typically split along a centerline of the container.
By using a flexible door on the front side of the air cargo container, cargo items may be loaded against the vertical rear wall of the container up to the top of the rear wall. Cargo may continue to be loaded up to the front of the container. The curved space in the container may be substantially filled smaller items, thus filling more of the available space within the container.
While this flexible door design allows more space in the air cargo container to be filled, it has several drawbacks. Initially, the straps and buckles on the netting and cover take a relatively long time to fasten together. Typically, three to four minutes are required to close a container using the flexible door design. In addition, the air cargo container does not include a storage area for the netting and the cover when they are in the open position. Thus, the netting and cover can fall in front of the opening, during loading or unloading. They may also move freely under windy conditions, causing damage to themselves or to the cargo or the container.
Moreover, if cargo shifts during transport, it can lodge against the netting, causing tension in the netting and the belts. If there is significant tension in the netting and/or belts, opening the flap door can be difficult or even dangerous. Finally, because the flexible door is made of netting, it cannot act as a template or indicator that no cargo is protruding out of container and may cause interference when the container is loaded onto an aircraft. Cargo items can protrude through openings in the netting. Thus, the air cargo container cannot always be fully loaded, since determining whether the flexible door is within the profile necessary for safe loading into the aircraft, must be estimated visually.
Therefore, an air cargo container that may be efficiently loaded and unloaded through a curved side of the air cargo container is needed.